1. Field of the Invention
This invention relates to regulated attachment for interior rearview mirror assemblies mounted to a button on the interior of a vehicle windshield.
2. Scope of the Prior Art
Interior windshield-mounted rearview mirrors are commonly used in nearly all vehicles manufactured and sold throughout the world. Different mounts have been designed for different vehicles and are subjected to varying regulations of the different countries in which automobiles and similar vehicles are manufactured.
In the United States and Canada, for example, supports for conventional windshield-mounted rearview mirrors typically include a base member, known commonly as a "button", adhered to the inside of the windshield surface. The button has vertically disposed edges forming rails. The rails may be formed by a bevel on each edge. A support member, known in the industry as a "channel mount" is slidably fitted over the button whereby sides of the channel mount engage the rails of the button. The channel mount usually includes a mounting means such as an arm, ball joint, or other structure for suspending a rearview mirror in the vehicle compartment for use by the driver of the vehicle. A typical mounting assembly in U.S. vehicles includes a linkage with a double ball joint for adjusting the mirror relative to the windshield in a variety of positions.
Typically, the channel mount is retained on the button by the use of a set screw operatively engaging the button. However, the use of such a set screw has created numerous manufacturing and maintenance problems in the vehicle assembly. For example, set screws are typically purchased as low-priced commodity items with low tolerances in the screw threads. The inconsistency in such threads can result in cross threading of the screw in its aperture. Sometimes, automatic screwdrivers stop prematurely at a preset stall torque even though the support is not firmly tightened against the button. Sometimes the screws fit so sloppily that there is no torque. Also, the set screw is often stripped out by overtightening because of the improper sizing of the socket to the set screw or a weakness in the threads of the screw itself.
Attempts have been made in the past to design interior mirror mounts without the use of a set screw. An example may be found in U.S. Pat. No. 4,936,533 issued to Adams et al. on Jun. 26, 1990. This patent discloses a vehicle accessory mounting assembly comprising a spring retainer on the channel mount which is adapted to engage and grip an opposing, raised rib on the surface of the button. The Adams et al. design, however, presents some problems in that it requires a specially designed button and it is virtually impossible to disassemble without utilizing a special tool.
The U.S. Pat. No. to Aikens et al., 4,254,931, (issued Mar. 10, 1981) discloses an interior rearview mirror mount wherein a spring clip on a mounting member slides over a button on a windshield to provide a breakaway mount. The button has a plurality of serrations in an inner face thereof. The spring clip has a lock spring which engages the serrations to prevent easy sliding of the mounting member from the button. The Aikens et al. mount requires a special button which differs from buttons now in use. Further, the plurality of serrations may give a false and unregulated impression as to whether the mount is fully seated on the button.
Efforts to provide a regulated attachment for a rearview mirror were substantially enhanced by the spring clip construction disclosed in a U.S. Pat. No. to Suman et al, 5,377,948 (issued Jan. 3, 1995). Regulation of the securement is effected by a part of the die cast support or spring clip moving into a final assembled position with sufficient authority to signal the assembler that the support is fully seated on the button. The tolerance relationship between the spring clip and the button determines or regulates, based on the positional relationship between the spring clip and the button, the degree to which the support is fastened to the button. This construction revolutionized the assembly of a rearview mirror to a button by reason of providing a readily perceived signal to the installer that the integrity of the securement of the support to the button is to the required standard.
A need continues to exist for a regulated attachment mechanism for an interior rearview mirror mount which is easy for the installer to perform the required assembly, which is capable of retaining a mirror element in a stable position, is configured to be usable in the majority of vehicles which have varying windshield areas, angles of inclination, and radii of curvature, which will, if desired, readily break away from the button when subjected to an impact of predetermined magnitude, which is nevertheless readily removable for replacement, and which is aesthetically pleasing and capable of high-volume production at reduced manufacturing cost from that heretofore experienced and still provides consistent assembly time after time which meets the tolerance requirements and automobile safety standards.